<!DOCTYPE html>  
<html lang="en">  
<head>  
<meta charset="UTF-8">  
<title>简单时分秒倒计时</title>  
<script type="text/javascript">  
    function countTime() {  
        //获取当前时间  
        var date = new Date();  
        var now = date.getTime();  
        //设置截止时间  
        var endDate = new Date("2017-10-27 16:35:23");  
        var end = endDate.getTime();  
        //时间差  
        var leftTime = end-now;  
        //定义变量 d,h,m,s保存倒计时的时间  
        var d,h,m,s;  
        if (leftTime>=0) {  
            d = Math.floor(leftTime/1000/60/60/24);  
            h = Math.floor(leftTime/1000/60/60%24);  
            m = Math.floor(leftTime/1000/60%60);  
            s = Math.floor(leftTime/1000%60);                     
        }  
        //将倒计时赋值到div中  
        document.getElementById("_d").innerHTML = d+"天";  
        document.getElementById("_h").innerHTML = h+"时";  
        document.getElementById("_m").innerHTML = m+"分";  
        document.getElementById("_s").innerHTML = s+"秒";  
        //递归每秒调用countTime方法，显示动态时间效果  
        setTimeout(countTime,1000);  
    }  
</script>  
</head >  
<body onload = "countTime()">  
    <div>  
        <span id="_d">00</span>  
        <span id="_h">00</span>  
        <span id="_m">00</span>  
        <span id="_s">00</span>  
    </div>  
</body>  
</html> 